The present invention relates to an apparatus for recording compressed video and audio signals on a medium such as an optical disk or the like and reproducing such signals from such a medium.
A compression of video and audio signals has been described in detail in Jun Yonemitsu (editorial supervisor), xe2x80x9cMPEG Techniquexe2x80x9d, pp. 12-21, published in Japan by Trikeps on Dec. 21, 1993. An example of an optical disk has been described in detail in Kenji Hayashi (editor and author), xe2x80x9cCDxe2x80x94From Audio to Personal Computerxe2x80x9d, pp. 84-89, published in Tokyo, Japan, by Corona Publishing Co., Ltd., on Jul. 25, 1990.
A compression method of the video and audio signals and a corresponding decompression method have been described in the first reference listed above. A signal recording format of a CD (compact disc) has been described in the second reference listed above. However, a method of easily realizing a retrieving method when the compressed video and audio signals are recorded on a medium and are reproduced therefrom is not described.
In the case of reproducing the medium such as a CD or the like on which the compressed video and audio signals have been recorded in a data stream format as described in the xe2x80x9cMPEG Techniquexe2x80x9d reference listed above, a picture or a boundary of a group of pictures can be judged by reproducing the data stream and judging header information of a pack and a packet. In the case of recording a signal on the medium, however, in order to improve an error resistance, an interleave process and an error correction encoding process which are peculiar to the medium and a frame forming process involving addition of a sync signal and sub information are ordinarily executed. When the picture or boundary of the picture group is judged by reproducing the data stream and judging the header information of the pack and the packet, therefore, a position of a pickup or the like which is reproducing data from the medium has already been deviated. Therefore, in the case of performing a retrieval, an editing operation and the like on a picture or picture group unit basis, a complicated control is needed to find a position of the picture or boundary of the picture group on the medium, so that there is a problem such that it takes a long time to find the position.
It is an object of the invention to provide a transmitting and recording method, a reproducing method, and a reproducing apparatus of information which are suitable for retrieving and editing on a picture or picture group unit basis.
The above object is accomplished by a method whereby when time sequential data of a pack is divided into a minimum unit of a data structure which is peculiar to a medium and is transmitted or recorded on the medium, information indicating whether a picture or a boundary of a picture group exists in the minimum unit of the data structure peculiar to the medium or not is described in a sub information portion in a frame signal to be transmitted or recorded when a frame forming process that is peculiar to the medium is executed.
In the case of performing a retrieval, an editing operation, or the like on a picture or a picture group unit basis, by reading the information which was reproduced from the medium and was written in the sub information portion in the frame signal peculiar to the medium and indicates whether the picture or the boundary of the picture group exists in the minimum unit of the data structure peculiar to the medium and by judging, a reproducing position on the medium at which to reproduce the picture or the boundary of the picture group can be accurately and easily detected. Thus, a complicated control to find the position of the picture or the boundary of the picture group is unnecessary, so that the picture or the boundary of the picture group can be retrieved at a high speed.